Ordering of NAL units in coded video

Abstract

Examples of video encoding methods and apparatus and video decoding methods and apparatus are described. An example method of video processing includes performing a conversion between a video and a bitstream of the video. The bitstream includes one or more layers including one or more network abstraction layer (NAL) units according to a format rule that specifies that a first layer identifier in a header of an end of sequence network abstraction layer (EOS NAL) unit is required to be equal to a second layer identifier of one of the one or more layers in the bitstream.

What is claimed is: 
     
       1. A method of video processing, comprising:
 performing a conversion between a video and a bitstream of the video according to a first format rule and a third format rule, 
 wherein the bitstream comprises one or more layers comprising one or more network abstraction layer (NAL) units, 
 wherein the first format rule specifies that a first layer identifier of an end of sequence network abstraction layer (EOS NAL) unit is required to be equal to a second layer identifier of one of the one or more layers in the bitstream, and 
 wherein the third format rule specifies that a picture unit (PU) of a particular layer after an EOS NAL unit of the particular layer shall be an intra random access point (IRAP) PU or a gradual decoding refresh (GDR) PU. 
 
     
     
       2. The method of  claim 1 , wherein the first format rule further allows for inclusion of more than one EOS NAL units in a PU. 
     
     
       3. The method of  claim 1 , wherein the first format rule specifies that the first layer identifier of the EOS NAL unit is required to be less than or equal to a third layer identifier of a video coding layer (VCL) NAL unit associated with the EOS NAL unit. 
     
     
       4. The method of  claim 1 , wherein the conversion is performed according to a second format rule,
 wherein the bitstream comprises one or more layers comprising one or more PUs comprising one or more NAL units, and 
 wherein the second format rule specifies that, responsive to a first NAL unit indicating an end of sequence in a PU, the first NAL unit is a last NAL unit among all NAL units within the PU other than another NAL unit, if present, indicating another end of sequence or indicating an end of the bitstream, if present. 
 
     
     
       5. The method of  claim 4 , wherein the another NAL unit is an EOS NAL unit. 
     
     
       6. The method of  claim 4 , wherein the another NAL unit is an end of bitstream (EOB) NAL unit. 
     
     
       7. The method of  claim 4 , wherein the PU comprises a picture header NAL unit, a coded picture comprising one or more video coding layer NAL units and zero or more non-video coding layer NAL units. 
     
     
       8. The method of  claim 1 , wherein the performing the conversion comprises encoding the video into the bitstream. 
     
     
       9. The method of  claim 1 , wherein the performing the conversion comprises decoding the video from the bitstream. 
     
     
       10. The method of  claim 1 , wherein the conversion is performed according to a fourth format rule,
 wherein the fourth format rule specifies that, when present, an EOS raw byte sequence payload (RBSP) syntax structure specifies that a next subsequent PU that belongs to a same layer as the EOS NAL unit in the bitstream in a decoding order is of a particular PU type from an IRAP PU type or a GDR PU type. 
 
     
     
       11. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:
 perform a conversion between a video and a bitstream of the video according to a first format rule and a third format rule, 
 wherein the bitstream comprises one or more layers comprising one or more network abstraction layer (NAL) units, 
 wherein the first format rule specifies that a first layer identifier of an end of sequence network abstraction layer (EOS NAL) unit is required to be equal to a second layer identifier of one of the one or more layers in the bitstream, and 
 wherein the third format rule specifies that a picture unit (PU) of a particular layer after an EOS NAL unit of the particular layer shall be an intra random access point (IRAP) PU or a gradual decoding refresh (GDR) PU. 
 
     
     
       12. The apparatus of  claim 11 , wherein the first format rule further allows for inclusion of more than one EOS NAL units in a PU, and
 wherein the first format rule specifies that the first layer identifier of the EOS NAL unit is required to be less than or equal to a third layer identifier of a video coding layer (VCL) NAL unit associated with the EOS NAL unit. 
 
     
     
       13. The apparatus of  claim 11 , wherein the conversion is performed according to a second format rule,
 wherein the bitstream comprises one or more layers comprising one or more PUs comprising one or more NAL units, and 
 wherein the second format rule specifies that, responsive to a first NAL unit indicating an end of sequence in a PU, the first NAL unit is a last NAL unit among all NAL units within the PU other than another NAL unit, if present, indicating another end of sequence or indicating an end of the bitstream, if present. 
 
     
     
       14. The apparatus of  claim 13 , wherein the another NAL unit is an EOS NAL unit. 
     
     
       15. The apparatus of  claim 13 , wherein the another NAL unit is an end of bitstream (EOB) NAL unit. 
     
     
       16. The apparatus of  claim 13 , wherein the PU comprises a picture header NAL unit, a coded picture comprising one or more video coding layer NAL units and zero or more non-video coding layer NAL units. 
     
     
       17. A non-transitory computer-readable storage medium storing instructions that cause a processor to:
 perform a conversion between a video and a bitstream of the video according to a first format rule and a third format rule, 
 wherein the bitstream comprises one or more layers comprising one or more network abstraction layer (NAL) units, 
 wherein the first format rule specifies that a first layer identifier of an end of sequence network abstraction layer (EOS NAL) unit is required to be equal to a second layer identifier of one of the one or more layers in the bitstream, and 
 wherein the third format rule specifies that a picture unit (PU) of a particular layer after an EOS NAL unit of the particular layer shall be an intra random access point (IRAP) PU or a gradual decoding refresh (GDR) PU. 
 
     
     
       18. The non-transitory computer-readable storage medium of  claim 17 , wherein the conversion is performed according to a second format rule,
 wherein the bitstream comprises one or more layers comprising one or more PUs comprising one or more NAL units, and 
 wherein the second format rule specifies that, responsive to a first NAL unit indicating an end of sequence in a PU, the first NAL unit is a last NAL unit among all NAL units within the PU other than another NAL unit, if present, indicating another end of sequence or indicating an end of the bitstream, if present. 
 
     
     
       19. The non-transitory computer-readable storage medium of  claim 18 , wherein the another NAL unit is an EOS NAL unit or an end of bitstream (EOB) NAL unit. 
     
     
       20. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:
 generating the bitstream of the video according to a first format rule and a third format rule, 
 wherein the bitstream comprises one or more layers comprising one or more network abstraction layer (NAL) units, 
 wherein the first format rule specifies that a first layer identifier of an end of sequence network abstraction layer (EOS NAL) unit is required to be equal to a second layer identifier of one of the one or more layers in the bitstream, 
 wherein the third format rule specifies that a picture unit (PU) of a particular layer after an EOS NAL unit of the particular layer shall be an intra random access point (IRAP) PU or a gradual decoding refresh (GDR) PU.